Recent years have witnessed an increasing demand for a high-performance, low-cost liquid crystal display panel together with widespread use of information equipment.
A high-performance liquid crystal display panel is produced with use of, for example, a known technique called polymer sustained alignment (PSA).
PSA is a technique that adds, as an alignment film material, a monomer to a liquid crystal material for display use and that polymerizes the monomer to form, on a first alignment film, a layer [polymer layer (polymer film)] as a second alignment layer. Specifically, a pair of substrates each including a first alignment film are combined with each other in such a manner that the respective first alignment films face each other and a cell is formed between the substrates. Then, a liquid crystal material including a monomer is injected into the cell, and the liquid crystal molecules are aligned in a predetermined direction through, for example, application of an electric field. In this state, the monomer is polymerized by, for example, ultraviolet irradiation. This polymerization forms, on each of the first alignment films, a polymer layer that provides a tilt to liquid crystal molecules at the interface. This operation causes liquid crystal molecules in contact with the polymer layer to be fixed at a pre-tilt angle.
Patent Literature 1, for example, discloses a liquid crystal display device that is produced by (i) injecting a liquid crystal composition containing a polymerizable monomer between two substrates and (ii) polymerizing the monomer while applying a voltage across a transparent electrode sandwiched by the substrates facing each other. The polymerizable monomer includes (i) at least one ring structure or condensed structure and (ii) two functional groups directly bonded to the at least one ring structure or condensed structure. This liquid crystal display device thus has reduced screen burn-in.